1. Field of the Invention
The present invention relates to an antenna, more particularly to a folded multi-strip monopole antenna, in which it can be miniaturized by reducing the height thereof.
2. Description of the Related Art
Recently, researches have been extensively made in order to develop a technology related to an ultra wideband (UWB) communication. The UWB communication is regarded as a core technology in the next generation wireless communication. The UWB communication does not use a carrier wave, which is used to transmit a base band signal in a general wireless communication system. Instead, it uses a low power pulse having a signal time slot of only one nanosecond to a few picoseconds. It transmits a low power signal over a broad frequency band, so that the power consumption is less than the conventional systems. It shares the frequency band used by the conventional narrowband systems, without any separate allocation of an available frequency band, so that limited frequency resources can be used efficiently. Moreover, the UWB communication is capable of very delicately tracking an object, and thus is applicable to imaging systems such as a radar or a ground penetration radar system (GPRS). It can realize a data transmission rate of more than ten times that of a general wireless local area network (LAN).
Since a broad frequency band from 3.1 GHz to 10.6 GHz is used in this UWB communication technology, a wideband antenna, which can transmit and receive a signal in a broad range of frequency, is necessarily required. In addition, according to the miniaturization of communication equipments due to the advanced technology, a small antenna is strongly required. There is, therefore, a need to develop an antenna, which can meet a wideband characteristic suitable for the UWB communication technology and can also be miniaturized.
Antennas having a wideband characteristic meeting the UWB bandwidth are exemplified by a biconical antenna, a horn antenna, a reflector antenna, a spiral antenna, and a log periodic antenna, etc. However, a biconical antenna, a horn antenna, and a reflector antenna are relatively large in their size, so that they can hardly satisfy the requirements for small antennas. A spiral antenna and a log periodic antenna cause a dispersion due to the radiation time difference between a low and high frequency with respect to an impulse signal composed of wideband frequency signals, not a narrow band sinusoidal wave, and thus it leads to a distortion in the transmitted and received signal.